The present invention relates to a novel process for producing puffed, inflated, or swollen foods (hereinafter referred to as "swollen" food(s)) and to a specific article of swollen food.
Various attempts have so far been made to obtain swollen foods by heating and pressurizing starchy materials such as flour and cornstarch or proteinous materials such as soybean protein through an extruder and then swelling the same by sudden release of pressure.
While swollen foods can be produced by such conventional methods generally with high efficiency, the swollen foods obtained heretofore have generally been liable to have coarse swollen cells or foam bubbles formed by foaming although depending upon the compositions of the foods. When the swollen cells or foam bubbles are coarse, i.e., large, the cell membranes are generally thick so that the whole swollen food becomes hard, resulting in a hard mouth feel. Consequently, such swollen foods have had the problem, for example, of being unsuitable for infant foods such as baby foods.
Further, in one specific mode of the above method for producing swollen foods in which a food material predominantly comprising a starchy material such as flour is mainly used, the total water content in the starting materials fed to an extruder is maintained at about 40% and the extruder used has a die outlet with a square cross section, the swelling percentage of an extrudate at the die outlet is low since the water content is somewhat higher than in starting materials ordinarily used, so that an extrudate having a square cross section approaching that of the die can be obtained. This extrudate, for example, is then cut to an appropriate length, and water contained therein in excess is removed by drying, whereby it can be expected that crouton-like articles can be obtained as the end product.
Although, when sprinkled over hot soup, the swollen food thus prepared does not soften (or become "mushy") in a time period as short as about 10 to 30 seconds, it is not crispy and feels so hard in the mouth that it is far from being a crouton from the standpoint of textural feel in the mouth.
Conventional croutons prepared by dicing bread into cubes and drying the so diced bread, on the other hand, can be easily crushed when they are eaten directly but, when sprinkled over hot soup, soften in about 20 to 30 seconds and do not feel crispy, thus losing somewhat their pleasant mouth feel.